It was the middle of the night when Karen Murray’s 9-year-old daughter called out for her and she jumped out of bed to see if everything was OK. The next thing she remembers, her legs gave out from under her and she fell, hitting her head on the nightstand on her way down. “I blacked out,” says the 44-year-old. “A few seconds later, I came to and got up, but I felt wobbly and nauseous.” Her husband went to check on their daughter, and Murray spent the next 20 minutes feeling like she was going to throw up. When the nausea passed, Murray drifted back to sleep.
But the next morning, the mum of two woke up with a pounding headache. Throughout the rest of the day, she had bouts of nausea and dizziness. While waiting for her son’s soccer practice to finish, Murray called her mum, who’s a nurse, explaining what had happened the night before and how she still felt “off.” Her mother urged her to go to the emergency room, worried her daughter had suffered a concussion.
“I wasn’t thinking I had a concussion,” says Murray. “I’d always thought that only happened to football players, or after a serious accident like a car crash.” Yet when she went to the hospital, the emergency doc ordered a CT scan and sure enough, Murray was diagnosed with a mild concussion.
Abigail Bretzin PhD, a sport-related concussion researcher isn’t surprised that Murray didn’t initially recognise that her head injury might be as serious as it was. “It really hasn’t been recognised that concussion and traumatic brain injuries happen as often as they do in women,” says Bretzin, who researchers sex differences in outcomes of concussion. “In general, the focus has been on men. And while men do have higher rates of concussion than women overall, we also know that women’s brains may be more vulnerable.” Understanding why—as well as the signs and symptoms of a brain injury—can help you keep your brain protected for years to come.
What a concussion does to your brain
The word concussion comes from a Latin word that means to shake violently, explains Bretzin. “When you hit your head, the impact imparts forces to your brain, and those forces lead to a cascade of events that can cause a range of symptoms.”
Dr Douglas Smith studies this neurometabolic cascade. “You can think of your brain like an electric grid, with a network of fibres coursing throughout this crucial organ,” says Dr Smith. “The impulse starts in the grey matter on the outside of the brain and moves to the white matter on the inside, which is filled with axons—little fibres that are so small and delicate that you’d need to put 100 of them side by side to be as thick as one human hair.” The axons are like the brain’s wires in this electrical grid, transporting information from neuron to neuron so we can do everything from breathe and talk to read and move all of our muscles.
The axons are able to do this thanks to sodium channels that run through them, which work a little like a toilet tank: A flapper valve lets just the right amount of sodium into the axon to get a spark that creates electricity, which then gets passed down the axon. When the axon has enough sodium, the valve shuts.
But let’s say you bang your head like Murray did. The impact can stretch those axons so abruptly that they break, explains Dr Smith, which in turn breaks the valve. The result? Too much sodium rushes into the axons, overwhelming them and prompting an electrical “brown-out” that’ll cause you to feel dazed, confused, have a slower reaction time, and even lose consciousness. Because it takes a while for your brain to pump out all that excess sodium, those quintessential symptoms of a head injury—headache, confusion, dizziness, trouble focusing, and more—persist. As your brain tries to regulate itself and get back to normal, you are even more susceptible to another injury, adds Bretzin, which is why doctors warn concussion patients of the importance of not re-injuring the brain in the weeks after a blow to the head.
What happens after a concussion
The good news is that most people who experience a concussion fully recover—about 80% do fine, says Dr Smith. And researchers are trying to figure out exactly why the other 20% don’t fare as well. But even though the odds are in your favour of a full recovery after a head injury, seeking medical attention is crucial—even if you’re starting to feel a bit better, warns Dr Smith. “The reason we take head injuries so seriously and almost always order a CT scan is so that we can check for bleeding in the brain, which can cause those axons to expand and kill them—and you.”
Earlier care also helps target treatment approaches that can lead to better outcomes, says Bretzin. “Not everyone with a concussion presents with the same symptoms, which can make it tricky to diagnose and treat,” she says. “But if we can monitor your symptoms, we can better direct you to treatments that may help prevent a long-term effect.” For example, if your balance is off after a head injury, you may need to see a physical therapist; cognitive impairments, like brain fog or a shorter attention span, might require a visit to a neuropsychologist.
The XX factor: Why women’s brains are more vulnerable
Luckily, a CT scan of Murray’s brain the day after her fall showed no internal bleeding. But her symptoms did persist for about three months. She got frequent headaches and found that looking at her computer screen or watching TV for more than an hour at a time led to intense head pain.
Smaller bodies, bigger problems
These continued concussion symptoms may have something to do with anatomical differences between males and females, which cause women to have more severe symptoms than men and take a longer time to recover after a concussion, says Angela Colantonio PhD, who researches traumatic brain injuries. For starters, women tend to have smaller and thinner necks than men, which makes them more vulnerable to the rotational forces that can injure the brain, says Colantonio. In one study of female soccer players—who are more than twice as likely to suffer concussion as their male counterparts—researchers found women had a significantly greater head and neck “angular acceleration,” a measure of head impact that’s thought to be a cause of brain injury. “These biomechanical differences mean that men’s stronger necks are better able to resist against head impacts that cause concussion,” says Bretzin.
There are also anatomical differences inside the brain that may play a role in making the female brain more vulnerable after a head injury, adds Dr Smith. If you look at axons in men compared to women, women’s axons tend to be smaller. “When we do in vitro models—where we take human neurons and micropattern them into a human brain—and induce the same kind of rapid stretching of those axons that happens in concussion, we find there’s far less swelling and sodium influx in male axons compared to females,” says Dr Smith. “The exact same impact pushes female axons toward bad pathways—like persistent sodium issues in the brain and more disconnection of axons—whereas men seem to rebound.” Researchers think this larger axon size makes the male brain better able to sustain impact.
How oestrogen fits in
Hormones may also play a role in how women fare after a ding to the head, adds Colantonio. In fact, research shows a clear correlation between a woman’s menstrual cycle and how well (or not) she’ll recover from a brain injury. One 2014 study found that women who suffer a concussion during the luteal phase of their menstrual cycle (the two weeks after ovulation, when oestrogen and progesterone levels are highest) leads to worse outcomes a month later than women whose head injuries happened during the follicular stage (the two weeks following menstruation, when those two hormones are at their lowest levels). Interestingly, women taking oral contraceptives and those past menopause also fared better after concussion. The researchers’ theory is that a blow to the head can suppress the pituitary gland. Aka, the brain’s hormone control centre. If the pituitary slows down when hormones are high, a rapid decline of those hormones makes symptoms worse and stick around longer; if hormones are already low, that drop-off has less of an impact.
The other dangers of being a woman
Then, there are correlations related to gender, adds Colantonio, “which isn’t about the biological attributes of men versus women but rather our socially constructed roles.” For example, consider the gender-based violence prevalent around the world, with one in three women victim to intimate partner violence at some point in their lives. “The head, face, and neck are common areas of injury,” says Colantonio, “and those injuries tend to be repetitive.”
How to protect your brain from concussion
While you can’t isolate yourself from everything that poses a risk for a head injury, experts agree there are a few smart steps you can take.
Step 1: Think about how you can minimise your risk of falling.
Bretzin’s current research is currently focused on how to stop concussions from happening in the first place. “The answer could be as simple as eliminating some risky behaviours or using protective equipment, like a proper-fitting helmet when you ride a bike,” she says.
Colantonio says it’s also important to recognise that one of the biggest segments of the population who get concussions are older adults, which means it’s especially important to assess your risk of falls as you age. “It’s easy to think of falls as accidents, but there’s a lot you can do to prevent them,” she says. “Things like exercising to build balance and strength, getting enough sleep, not rushing when you get up, and even wearing well-fitting shoes can go a long way toward keeping you safe.” Colantonio even recommends working with an occupational therapist who can do a home safety assessment, checking for trip hazards and making suggestions for design tweaks to keep you safe.
Step 2: See a doctor immediately after a bump to the head.
Detecting and treating a head injury as soon as possible is one of the most important things you can do, says Bretzin. “Seeking out healthcare immediately after you’re injured can really help prevent or mitigate lasting effects of the injury,” she says. Dr Smith agrees, adding that seeing a specialist is especially important if you’ve been diagnosed with a concussion. “If you hit your head and go to your GP, he or she may not know who to refer you to,” he says. “Ask for a concussion expert, who’ll have more training in head injuries and can point you to specific rehabilitation treatments and possibly even clinical trials.”
Step 3: Understand there are things you can do to soften the potential lasting effects of a concussion.
For many people who’ve experienced a head injury, symptoms resolve. Yet some—especially women—may experience long-term effects. If you fall into this group, it’s important to pipe up about your pain, says Bretzin. “Talk to your doctor or other healthcare providers about your understanding that women are at greater risk of persistent symptoms after concussion,” she says. “Ask about rehab programs and support groups for other concussion survivors. It’s important to recognise that your symptoms may require continued care and management, and there are specialists who can help you along this path.”